The present disclosure relates to methods for the manufacture of microelectronic workpieces, and in particular, methods to etch material layers on microelectronic workpieces.
Device formation within microelectronic workpieces typically involves a series of manufacturing techniques related to the formation, patterning, and removal of a number of layers of material on a substrate. To meet the physical and electrical specifications of current and next generation semiconductor devices, processing flows are being requested to reduce feature size while maintaining structure integrity for various patterning processes.
Extreme ultra-violet (EUV) techniques have been used for photolithography processes to achieve reduced feature size in the manufacture of microelectronic workpieces. Because EUV photoresist patterns have very small dimensions, patterned photoresist (PR) is often unable to maintain its pattern during subsequent etch processes. Further, increases in aspect ratios for patterned structures from further scaling and greater density promotes the onset of pattern collapse. Prior solutions have tried to reduce the risk of pattern collapse by changing the photoresist hardness through composition or molecular configuration (bonding) changes. However, pattern collapse has still occurred with these prior solutions.
FIG. 1A (Prior Art) is a cross-section diagram of an example embodiment 100 where a patterned photoresist layer 102 has been formed over an underlying layer 104. The underlying layer 104 is formed over a substrate 106 for a microelectronic workpiece, and the substrate 106 can include one or more previously formed layers or structures. The underlying layer 104 represents a material layer to which the pattern from the patterned photoresist layer 102 is to be transferred. For example, the underlying layer 104 can be an oxide (SiO2) layer, a nitride (SiN3) layer, a hard mask layer, and/or other material layer to which the pattern is to be transferred. The patterned photoresist layer 102 can be, for example, an EUV photoresist material.
FIG. 1B (Prior Art) is a cross-section diagram of an example embodiment 150 after an etch process has been performed to transfer the pattern from the patterned photoresist layer 102 to the underlying layer 104. During this pattern transfer process, however, the photoresist layer 102 suffers erosion as indicated by brackets 152 effectively damaging and breaking down the pattern. In particular, current materials used as EUV photolithographic materials do not hold up well to etch processes (e.g., plasma etch processes) used to transfer patterns during the fabrication of microelectronic workpieces (e.g., semiconductor wafers). This erosion of the EUV photoresist pattern is often severe enough to create defects in resulting electronic devices including patterning defects such as broken pattern features, miss-shaped features, and/or other pattern anomalies that can degrade performance of the intended pattern.